Reese Witherspoon and Jake Gyllenhaal have called it quits for a second time.

Only a few weeks after reuniting, the Rendition co-stars were clearly on the outs again while promoting their film at the Toronto International Film Festival last week.

An insider told Us Weekly, "This is the harshest split they've had. Reese told Jake it's best they don't talk at all." The pair had been dating off and on for about six months, but had never made their relationship public.

Still, there could be hope for yet another reconciliation. At a party during the festival, one witness to Reese and Jake's interaction said, "They seemed like a couple. Reese was happy and having a good time." Another source close to the duo confided to Us, "They're a rocky couple. It would not be a shock if they got back together."